The incorrectly dated plaque apparently remained in plain public view for nearly two years as countless thousands visited the attack site and, presumably, saw the sign, the New York Post reported Friday.
The large metal sign, one of several on the viewing wall's eastern side, was unveiled in August 2002 in "honor of the heroes" of the Sept. 11, 2001, terror attacks so that "the world community can reflect upon and remember the events that took place here, and draw strength and inspiration as we rebuild."
Justin Matley, 21, apparently spotted the error July 10 and promptly sent an e-mail to the Port Authority. On Monday he got an e-mail response from the authority, thanking him for noticing the gaff.
The authority also removed the erroneous sign.
"As soon as we were told about it, we took the sign down," said authority spokesman Steve Coleman. "It is in the process of being replaced."
Selena Gomez drops F-bomb, walks off stage during Jingle Ball performance
'SNL': 'Anchorman 2' cast, One Direction sing 'Afternoon Delight' [VIDEO]